Steel slag handling system



J. J. GRADY STEEL SLAG HANDLING `SYSTEM April 25, 1957 Filed Jan. 2v,1965 6 Sheets-Sheet 1 E226 535mm @2m INVENTOR John J. Grady ATTORNEYApril 25, 1967 J. J. @mm 3,316,075

STEEL SLAG HANDLING SYSTEM Filed Jan. 27, 1965 6 Sheets-Sheet 2 Kitchen-26 Charging Floor-24 y FIG. 2

John J. Grady ATTORNEY April 25, 1967 J. J. GRADY 3,316,075

STEEL SLAG HANDLING SYSTEM Filed Jan. 27, 1965 6 Sheets-Sheet 5 FIG.4

HVVENTOR v 2 John J. Grady (D n ATTORNEY April 25, 1967 J. .1. GRADYSTEEL SLAG HANDLING SYSTEM 6 Sheets-Sheet 4 Filed Jan. 27, 1965 FIG. 5

FIG.6

I9 2a(Magne1ic Ferrous Particles) Slag And Meal Magnetic FerrousParticles |920 |92b- Nan- Magnetic Particles INVENTOR FIG. 8

John J. Grady ATTORNEY April 25, 1967 J. J. GRADY STEEL SLAG HANDLINGSYSTEM 6 Sheets-Shea?l 5 Filed Jan. 27, 1965 FIG. 9

Charging Floor- 24) INVENTOR m m. F

John J. Grady ATTORNEY April 25, 1967 J. J. GRADY 3,316,075

STEEL SLAG HANDLING SYSTEM Filed Jan. 27, 1965 6 Sheets-Sheet 6 FIG. Il

Furnace Yord Level INVENTOR John J. Grady BY ha .ML/MM United StatesPatent 3,316,075 STEEL SLAG HANDLING SYSTEM John J. Grady, New Florence,Pa., assigner to international Steel Slag Corporation, Washington, D.C.,a corporation ofthe District of Columbia Filed Jan. 27, 1965, Ser. No.428,519 16 Claims. (Cl. 6S-19) This application is a continuation-impartof my copending applications Ser. No. 126,792 and Ser. No. 304,932,tiled lune 28, 1961 and Aug. 27, 1963, respectively, both now abandoned.

The present invention relates to a system for more efficient, faster andmore economical removal of slag discharged from steel-making furnaces,and recovery of ferrous material therefrom. More especially, the presentinvention relates to a new improved method and apparatus for convertingred-hot slag discharged from an openhearth furnace into a granularmixture of ferrous and slag particles of relatively small size and lowtemperature, and rapidly conveying the resultant granular mixture fromthe furnace building during the steel-making operation, with relatedmeans for transporting said granular mixture to and through a magneticseparator to reclaim the usable ferrous material and suitably dispose ofnonferrous slag.

For some years, steel in large quantities has most cornmonly been madein open hearth furnaces, in which ingredients such as scrap iron, pigiron, hot molten iron from blast furnaces, ore, limestone, etc., aremelted and refined to produce molten steel. A substantial quantity ofslag is formed over the molten steel bath in the open hearth furnace andplays an important part in the steelmaking process. Typically, the slagconstitutes about one-fifth of the total charge to the furna-ce in aheat;

ence, in a modern open hearth furnace having a capacity of 350 tons perheat, about 65 to 70 tons of slag are formed and must be disposed ofwithin a relatively short time. Generally a modern open hearth plantcontains to l5 stationary furnaces of 200 to 350 ton capacity, which aresubstantially continuously operated on staggered heat cycles, so that atremendous amount of slag must *be removed from the furnace buildingeach day.

Efficient quick removal of such large quantities of slag from adjacentthe open hearth furnaces and out of the furnace building is along-standing major problem in steel manufacture. This problem has beengreatly accentuated since World War II by the development of moderntechniques which make it possible to produce substantially greaterquantities of steel per heat in a substantially shorter time withexisting open `hearth furnaces. i Since World War II, the averageper-heat capacity of open hearth furnaces has been increased from about100 tons to about 20G-350 tons; and heat time, from tap to tap, has beendecreased from about 101/2-11 hours to about 8-81/2 hours. Increasinguse of oxygen and other improved operating techniques has now made ittechnically possible to reduce the heat time for a S50-ton furnace toabout 4 hours. It is estimated that a steel mill containing an openhearth lplant with eleven furnaces of S50-ton capacity per heat, plusrelated plant, represents a capital investment of about one hundredmillion dollars ($100,000,000-00). Also, it is estimated that thereduction of one minute of heat time from tap to tap represents a`saving of thirty thousand dollars ($30,000.00) per year for `such anopen hearth plant containing eleven furnaces. Thus, the tremendouseconomic significance of utilizing available techniques to operate openhearth furnaces at minimum heat time will immediately be apparent.Likewise, such operation of open hearth furnaces at minimum heat timewould greatly in- 3,316,075 Patented Apr. 25, 1967 ICC crease thenational defense capacity of the United States steel industry withexisting open hearth facilities.

The need for an eliicient system of removing increasingly largequantities of slag in a shorter, time, at reasonable cost, is thus amatter of serious concern to the steel industry.

For a long time, and until just a few years ago, it was common practicein leading mills to discharge open Ahearth slag into cast-iron slag potsremoved from the furnace room by rail cars. In this prior rail slag-potsystem, when the charge to the open hearth required a slag run-olf orflush during the heat (as when a high percentage of molten pig iron wasadded to the melt), provision was made for run-off of slag through anotch in the back wall of the open hearth furnace at one side of the taphole, whereby early slag passed through the run-off notch into a spoutand thence to a slag pot on rails behind the furnace. In addition, whenthe furnace was tapped at the end of the heat, the slag following themolten steel into the steel ladle would overow from the top of the ladleinto an adjacent slag pot through a slag spout extending from the ladleside. Then the ladle crane lifted the slag pot to a rail car on the pitside which was later removed to the slag yard. 'Early slag was sometimesalso removed by front flush from the furnace through a notch or troughcut in the refractory bank at the lower edge of the center furnace doorand thence through an opening in the charging floor into another slagpot set on a rail car at the yard level in the open hearth building.These slag pots were then removed by a locomotive from the open hearthfurnace building to a suitable disposal area where the slag was dumped,and then were returned to their aforementioned positions adjacent thefurnace` However, this rail slag-pot system proved inadequate andunsatisfactory for removal of greater tonnages of slag in less time, asopen hearth furnace capacity increased and melt time decreased.Consequently, leading steel plants have adopted a system in which partof the slag is front hushed from the center furnace door under thefurnace to the pit side, and the remainder of the slag is flushed fromthe steel ladle t-o the pit iloor when the furnace is tapped.Thereafter, highlift tractors and heavy-duty trucks are used to removethe slag from the pit side of the open hearth furnace buil-ding when thesteel ladle is removed after pouring the heat. (This current system isillustrated in FIGURES 13 of my earlier application, Ser. No. 126,792.)With a heat time of about 8 to 81/2 hours for a S50-ton furnace, about60 to 70 tons of hot slag must be removed `from below and behind thefurnace, loaded, trucked to a disposal point, unloaded, etc., in about lto 11/2 hours. If the slag is not removed from beneath the open hearthfurnace in this short time, while the open hearth furnace is :beingre-charged, as sometimes occurs, remaining slag under the furnace mustbe left there until after the next heat is completed. vBy then, thisslag has solidified and lbecomes very difficult to remove; moreover, thenewly formed slag from the next heat must also be removed in the limitedtime availa'ble while the furnace is again re-charged. In some mills, acostly heavy-duty tractor with a special stripper attachment ismaintained on a stand-'by basis to strip solidified slag from thefurnace pit, so that it can be loaded on trucks by the highlifttractors. Even though this special stripper equipment may 'be idle 85%of the time, it is deemed warranted t-o prevent much more costly loss offurnace operating time due to inadequate slag-removal operations.Furthermore, this slag rem-ofval operation is very rough on theequipment used, so that there are serious and continuous maintenanceproblems which potentially can cause a loss in furnace operating time,besides o requiring substantial maintenance facilities and reserveequipment.

The need for round-the-clock removal of high tonnages of slag has led touse in one of the most modern United States open hearth shops o-f atractor wagon capable of hauling 30 tons of hot slag, loaded by highlifttractors. This, however, involves an approach and problems similar tothose involved with the aforementioned highlift and truck system forhandling slag (more `fully discussed in my aforementioned parentapplication Ser. No. 126,792 with reference to FIGURES `1-3 thereof).

It has been apparent for some time that this currently -usedmultiple-step materials-handling system for removing open hearth slagafter tapping has serious inherent limitations, whereby it cannot 'besuccessfully utilized if the furnaces are run at the materially shorterheat times that are now feasible, and especially with four-hour heats.

The problems of handling and removing steel slag have been seriouslyincreased by the steel industrys rapid adoption, within the past fewyears, of oxygen steel-making furnaces, sometimes called OSM or BOFfurnaces. These furnaces are capable of producing steel in tremendousquantities in short heat times. For example, one steel company in theUnited States has :produced about 240 tons of steel in 27 minutes, tapto tap, compared'to 6 to 8 `hours in a modern open hearth furnace.However, such oxygen `steel furnaces also form large quantities of slagin the order of 12-l6% of the heat tonnage. Thus an OSM or BOF furnaceproducing about 250 tons of steel in one-half hour will also generateabout v37.5 tons of molten slag in one-half hour. These vast quantitiesof molten slag must be removed from the furnace and furnace building soas not to inuence the tap-to-tap capacity of the furnace and millproduction.

However, the prevailing method of handling and removing molten slagfrorn OSM and BOF furnaces is by use of a multiplicity of costly slagpots moved by cranes and/or rail cars from the furnace to a relativelyremote slag dump. These present multistep batch methods of handling OSM-or BOF steel slag are not only costly from the viewpoint of slaghandling, lbut also have serious inherent shortcomings limiting usefulcapacity of the furnaces. Improvement over such prevailing methods ofhandling and disposing of increasing tonnages of OSM Y or BOF slag'inless Itime has 'become critical in minimizing and avoiding productiondelays which may affect the entire mill, with tremendous economicramifications.

-For some time heretofore, blast furnace and other molten metal slagshave been granulated with water; but granulation of steel slags bysimilar techniques involves ldifferent problems whereby such watergranulation of steel slag was found dangerous and/or inoperative. Thisis summarized in Canadian Patent No. 562,523, on Method and Apparatusfor Handling Slag Resulting From Steel-Making Operations, issued toHarry V. Tomlinson on Aug. 26, 1958, from an application filed Mar. y17,1963, and assigned on its face (60%) to the I-Iarsco Corporation ofHarrisburg, Pennsylvania, a leader in the field of handling steel (andother) slag disposal for United States steel producers, said patentstating:

My invention, as a primary object, seeks to teach a practical method ofgranulating slag produced during various steel-making processes by theintroduction of the slag while in a molten condition into water, boththe slag and the water being controlled in accordance with the teachingsof the invention. In this respect the invention should be contrastedwith various heretofore known and/or suggested methods of granulatingblast furnace commercial application in the treatment of steel-makingslags.

It will be readily appreciated by those skilled in the art that slagsproduced in steel-making operations are tapped from the `furnace at aconsiderably higher temperature than are blast furnace slags. Thisfactor creates an unusual problem in that the higher temperaturesteelmaking slag tends to combine explosively with the waterV due to theextremely rapid generation of steam and liberation of hydrogen andcarbon monoxide gasses. Thus, methods heretofore known to `be effectivein the granulation of blast furnace slags have been found to bedangerous and/or inoperative when applied to the treatment ofsteel-making slags.

The aforementioned Harsco Canadian patent seeks to successfully andsafely granulate steel slag on a practical commercial basis by pouringthe molten `slag into a bath of water in a tank, with water fed into thetank below the water-bath surface and as low as one-half way to thebottom of the tank t-o create a water current in the bath at this level.Contrary to the objectives stated in the Canadian patent, the steel-slagsystem of that Harsco patent is susceptible lto explosion, land isdangerous, if not inoperative, aside from otherwise being impracticaland unacceptable from the viewpoint of real-life steel mill operations,for many reasons. Reportedly, the system of the Tomlinson-HarscoCanadian patent was tried for handling mol-ten steel slag, withresultant explosion, and was abandoned. In any event, although Harsco isone of the largest handlers of steel slag in the United States, it doesnot use the Canadian patent system for steel slag. Instead, the U. S.steel industry and its slag contractors, including Harsco, continue touse such above-discussed batch-type, multistep, slag handling systems,utilizing slag pots with rail cars, vehicles or cranes, -or highliftswith trucks and tractors, etc., in spite of the many shortcomings andproblems of such prior systems.

Hence, removal of steel slag by multiple-step batch systems has been andis a bottleneck that prevents the maximum utilization of existing openhearth and OSM and BOF furnaces, and the realization of tremendouseconomic savings and other advantages which .would be thus achieve-d.

It is therefore a primary object of this invention to :provide a newimproved slag-removal system which departs from the materials-handlingconcept of current and earlier `systems such as discussed above, thusavoiding their serious shortcomings and making it possible to achievecontinuous removal of the slag from the open hearth building as the slagis being dischargedy from the -furnaces during the heat. Moreparticularly, it is an object of the present invention to provide a newimproved slag-removal method and apparatus whereby the very hot slagfrom the open hearth furnace is discharged to a granulator wherein it issuddenly cooled and granulated by jets of water or the like -to formrelatively small discrete particles of ferrous and slag material, whichis then transported by continuous conveying Vmeans from the open hearthbuilding. It is another related object of this invention to thus achievecomplete removal of slag produced in a large heat within a very shorttime after the open hearth is tapped, whereby slag removal no longerconstitutes a bottleneck preventing optimum use of oXygen and shorterheat times in large capacity open hearth furnaces and OSM or BOFfurnaces.

It is another object of the present invention to proi vide such a newimproved slag-removal system by which the granulated slag and ferrousmaterial can be conveyed directly to magnetic separating means forquick, eficient, and economical separation of re-usable ferrous materialfrom the non-ferrous slag. It is another related object to thus provi-dethe steel mills with better control over the reclaiming of usableferrous material from open hearth slag, thus cutting the mills cost forsuch materials which are re-used in its open hearth furnaces.

meteore' It is still another object of this invention to provide such anew improved slag granulator removal and metal recovery system whichalso substantially reduces the high labor cost per ton of the currentlyused slag removal and recovery systems, and which also greatly decreasesthe cost of equipment per ton of slag removed compared to priorslag-removal systems. It is another related object to eliminate theserious and costly equipment maintenance problems encountered with thecurrently used slag-removal system, through resort to my new slaggranulating-and-particle-conveying system.

It is yet another object of the present invention to increase the safetyof slag-removal operations, thus furthering the diligent efforts of US.steel companies to continuously improve safe working conditions in themills, which is a matter of prime concern to the U.S. steel industry. Itis another related object of this invention to provide a water jetgranulator which has a novel arrangement and mode of operation wherebyit is capable of handling large tonnages of molten steel slag in a shorttime period, without creating explosions, or other dangerous orotherwise undesirable working conditions which the steel industry hasheretofore encountered in attempting to granulate steel slag with water.

It is another object of the present invention to provide such animproved slag-removal system incorporating means for diverting thefront-hush slag from the granulator to the pit below the open hearthfurnace, for re moval in conventional manner in the event that shouldprove necessary or desirable. It is a related object to provide a novelmovable slag discharge runner or spout arrangement for the slaggranulator, which chute is removable frorn below the front flushspillway to permit this alternate handling of the slag.

It is yet another object of this invention to provide various alternatesystems for handling steel ladle overflow slag, including a method andapparatus whereby the ladle slag is granulated in the same granulator asthe ront-Hush slag, in the kitchen of the open hearth furnace building,thus eliminating slagsremoval equipment from the pit iloor and pouringsine of the building. It is a related obiect to provide such systems inwhich ladle slag can also be diverted from the granulator to the pitfloor, if desired.

It is another object of this invention to provide such a novel improvedwater jet slag-granulatinganci-handling system which safely and rapidlyprocesses large tonnages of molten steel slag and therefore can be usedfor handling GSM and EGF steel furnace slags, for rapid processing anddisposal of high tonnages of such steel slag in minimum time, thusachieving various objectives and advantages more particularly discussedherein with reference to handling large tonnages of open hearth steelslag.

Other important objects and advantages of the present invention will beapparent from the foilowingdescription thereof with reference to theaccompanying drawings, and from the claims appended hereto, In thedrawings z FIGURE l is a perspective diagrammatic illustration of theoversall slag-removal system of the present invention;

FIGURE 2 is a diagrammatic cross-section of an open hearth furnace(along a line through the tap spout) showing one embodiment of theslag-removal system of this invention, including a granulator forconverting hot slag front flushed through the center open hearth doorand also the steel ladle slag;

FIGURE 3 is an enlarged side elevation view of the slag granulator withsteam removal and other related apparatus shown in the lower rightportion of FIGURE 2 (some parts being broken away for greater clarity);

FIGURE 4 is a top plan view of the slag granulator and related apparatusshown in FIGURE 3 (some parts being broken away for clarity);

FIGURE 5 is an enlarged top plan view of the water jet nozzles used inthe slag granulator shown in FIGURES 3 and 4 (portions thereof beingbroken away for clarity);

FIGURE 6 is an end elevation view of the granulator nozzle shown inFIGURE 5 (looking to the left at the nozzle in FIGURE 5);

FIGURE 7 is a side elevation view of the granulator nozzle shown inFIGURES 5 and 6 (a portion being broken away for a clearer showing);

FIGURE 8 is a schematic perspective showing of the conveyor, magneticpulley and splitter arrangement for separating magnetic ferrousparticles from non-ferrous particles in the granulated slag mixturewhich is conveyed from the granulator of FIGURES 2 and 3;

FIGURE 9 is a diagrammatic cross-section of an open hearth furnace(along a line through the center charging door, and similar to FIGURE2), showing in greater detail the movable-chute arrangement for the slaggranulator in the kitchen, whereby the chute which conveys thefront-ilush slag to the granulator can be removed from 4below thefront-flush spillway extending through the charging floor so that thefront-flush slag is diverted to the slag grade hill below the furnace;

FIGURE l0 is an enlarged perspective View of a preferred chute forconveying front-flush slag to the granulator in the kitchen asillustrated in FIGURE 9;

FIGURE 11 is a diagrammatic top plan view illustrating a modification ofpart of my improved slag-removal system shown in FIGURE 4, in thatanother granulator and conveyor system, etc. (per FIGURES 3-7) isprovided on the pit side of the open hearth for granulating slagdischarged from the steel vladles and then removing the same from theopen hearth furnace building, the granulator tank being mounted on arail car in the pit side so that it can be move-d from ladle to ladlebehind each of the furnaces, together with related conveyor means, etc;

FIGURE l2 is a diagrammatic cross-section of an open hearth furnace,illustrating the prior art practice of discharging front-flush slag fromthe charging door to below the furnace and the pit side, and thespill-olf of slag from the steel ladle to the pit floor, before removalby highlift tractor or truck.

In the following description, like numerals are used for like partsthroughout; in some instances, where parts are modified, comparableparts are identified by like numerals and subscripts, as explained whenapplicable.

Referring to drawing FIGURES l, 2, and 12, Vby way of background, atypical open hearth steel plant contains a plurality of open hearthfurnaces 2i) (usually ten to fourteen) installed in a line within thefurnace building generally indicated at Z2, as illustrated particularlyin FIGURE 1.

In a so-c-alled two-level shop, the furnace building 22 contains acharging tloor 24, which is usually about 22 feet above the general yardlevel of the building, with an area 26, called the kitchen, below thecharging door. The remainder of the floor space of the.` furnacebuilding located on the tapping side of the open heart-h furnaces 2t) iscalled the pit side or pouring door, which is indicated by numeral 28 inthe drawings and is at general yard level. The charging iloor 24 is laidwith various tracks (not shown) for operation of rail cars and chargingmachines for feeding scrap and/or pig iron into the open hearth furnaces20.

The open hearth furnaces 20 are `rectangular brick structures comprisinga front wall 30, a pan-type bottom 32, a back wall 34 which is usuallysloping, a roof 36, and end walls 37, which are lined with suitablehightemperature refractory material. This rectangular brick structure issupported on the sides, ends, roof, and bottom by steel framing which isdiagrammatically shown at 38 in t-he drawings. In FIGURE 2, there isschematically shown ian oxygen lance 45, whereby oxygen is introduce-dinto the steel bath yduring the steel producing process, greatlydecreasing the time per heat in modern open hearth furnace practice, aspreviously mentioned. Details of the open hearth furnaces and relatedequipment within the open hearth furnace building 22 are not shown ordescribed except to the extent helpful for full understanding of thepresent invention. 'For more details on open hearth furnaces andoperation thereof, see chapter 15 of The Making, Shaping land Treatingof Steel, 7th edition, United States Steel Corporation (1957), and itemsin the bibliography on pages 332-333 thereof.

The front wall of the open hearth furnace 20 contains a plurali-ty ofcharging openings 39 (usually five or seven in number); and each ofthese is cover-ed by a charging door 4t) that is vertically movablewithin watercooled frames 42 by a lifting cable or the like, indicatedat 44, which is usually operated by an electric door hoist. Each ofcharging doors is provided with `a peep hole d3, called a wicket, topermit inspection of the interior of the melting chamber of the openhearth.

Referring especially now to FIGURE 2, the rear furnace wall 34 isprovided with a tap hole `4,6 located midway between the ends of theopen hearth furnace `20, with its inner end at a low point of thefurnace hearth bottom 32. Tap hole 46 is adapted to communicate with atapping spout 48 when the tap hole 46 is unplugged at the end of a meltto remove the steel from the furnace. Below the outer end of the tappingspout 48, there is disposed a steel ladle 5t), which has a configurationsubstantially as shown in the drawings and i-s mounted on ladle stands52 by means of mounting blocks 54 extending from the sides of the ladle50 and resting on the stands 52 (as shown especially in FIGURE 12). Themounting blocks 54 on each side of the steel ladle 50 are provided withlaterally 'ex-tending Icylindrical trunnions 56, which are engageable bythe hook of an -overhead crane (not shown) for removal of the steelladle 50 after tappin-g of the open hearth furnace 20 to the ingotpouring platform (not shown). (See aforementioned text on steel making,especially Figure 15-1.)

The steel ladle 50 is also provided with a slag spout SS extendinglaterally from the upper edge of the ladle '50, which has a portionthereof cut out to permit overflow through spout 58 of slag poured intothe upper part of the ladle on top of lthe steel at the end of a furnacetap. The steel ladle 50 also is provi-ded with ya `stopper -rod andoperating means for pouring of the steel from the ladle, schematicallyshown at 6l) in the drawings.

FIGURE 1-2 shows a typical open heart-h furnace and steel ladlearrangement, and illustrates slag handling acco-rding to prevailingpractice in lea-ding mills. As shown especially in FIGURE 12, during thesteel-making operation, part of the slag overlying the steel bath in thefurnace 2@ is discharged through a notch or trough 62 cut in therefractory of the front -bank of the furnace at the center door 4l).rThis front flush slag 64, which is thus discharged from the `front sideof the furnace, passes through the opening in a hollow casting 66 set inthe char-ging floor 2d and into a pit 68 bel-ow the furnace, which isformed by spaced walls 70 extending from the 'yard level to theunderside of the furnace 20. The pit 63 below the furnace is filled withdirt or debris to form a hill 72, whereby the hot and viscous front-lushslag discharged through the lopening in charging oor 24 pours onto thishill and ows down it towards the pit side of the furnace, asschematically shown in FIGURE 12. Some of this front-flush slag spillsrdown to adjacent the steel ladle stands 52, while some of it cools tosuch extent that it remains in the pit `68 below the furnace 20. Thefront llushing of slag may continue for 1-11/2 hours in good operatingIpractice with a 350-ton furnace; but, at times, slag is front flushedat a very high rate, estimated as high as four tons per minute.

At the end of the steel-making heat, when the plug in rear :furnace taphole 46 is removed, the lower layer of steel runs from the ybed of theopen hearth furnace 2d through tap hole i6 and tapping spout d3 into thesteel ladle 54). Since the tapping hole 46 is located with its highestlevel at the lowest part of the furnace hearth and slopes downward tomeet the tapping spout 48, the greater portion of the steel flows out ofthe furnace before the slag in the furnace (which has not ibeen frontflushed). This slag then follows the steel through the tap hole 46 andtapping spout CSS into the steel ladle 50, on the top of the moltensteel. The ladle slag spout 58 is of suitable vertical dimension withrespect to the ladle 50 so that most of the excess slag flowing into theladle from the tapped furnace will overow the ladle Si), leaving,however, a small amount of slag as a covering for the steel in theladle, according to good practice. In the current slag-removal system,this `ladle slag 67 is discharged to the pit floor along side the ladlestand 52, as will be apparent from FlGURE 12.

After the steel has been poured and the slag/overflow 67 has beendischarged from the ladle, the tapping spout 4S is removed by a spouthoist (not shown) and the steel ladle 5d is removed from the supportingladle stands 52 to the ingot molds at the pouring platform, by one ofthe pouring cranes. Then highlift tractors or loaders promptly begin toremove the semi-molten slag from the pit floor 23 behind the furnaces,and load the slag onto heavy-duty trucks, which carry the slag from thefurnace building. In order to remove the front-flush slag from the pit68 below the furnace 2t), it is necessary for the highlift tractor tooperate within this pit, in quite close quarters between the adjacentwalls 70 below the furnace. Sometimes, in order to clear the slag frombelow the furnace 2li in the limited time before the furnace isrecharged and ready for the next melt, the front-flush slag 64 is movedto alongside the ladle stand S2 by the tractor operation and then laterloaded on trucks, since there is more time available for removal of theslag which is not below the furnace proper. The highlift bucket canhandle about 5 tons of slag, and semi-molten hot slag is loaded by thehighlift tractors on trucks (or tractor wagons) in rather huge lumps,each of which may weigh tons.

Usually, the trucks must carry away several loads of slag for completeremoval of the slag discharged from a 350-tcn furnace heat. Aspreviously mentioned, sometimes the slag cannot be removed from the pit68 below the furnace 2lb before the next heat is ready, and'must be leftfor removal after completion of the next heat together with the new slagthen discharged.

The hot slag loaded on the trucks (or tractor wagons) is transported toa so-called skull crackerr where the large slag pieces are broken up bydropping a weight on them, whereafter the larger more readilyretrievable usable ferrous material is separated from the non-ferrousslag, generally by a magnetic-crane operation. This larger usable'ferrous material is ultimately returned to the open hearth furnaces formaking of steel, and the remaining mixture of slag and ferrous materialis generally transported to ya recovery dump.V Subsequently the latterslag-and-metal mixture is processed in a sizingandseparating system foradditional recovery of reusable ferrous material, usually by breakingthe slag and metal into relatively Vsmall particles and then separatingferrous material from slag, by known techniques. The additional usableferrous material thus recovered is ultimately transported to the openhearth furnace for re-use, and the non-ferrous slag and gangue istransferred to a dump or other disposal point.

While this currently used slag-removal system is a substantialimprovement over the rail slag-pot removal systemV previously used, itwill be apparent that such slag removal by highlift tractors and trucksor tractor wagons has definite limitations. lt is, therefore, provinginadequate for removal of larger tonnages of slag in shorter periods oftime as the heat time of open hearth furnaces is decreased, therebygreatly decreasing the already limited time available for the tractorsto remove and load the slag, especially the front-flush slag, whichrepresents about 65% of the total slag and must be removed from belowthe furnace before the next heat is started. Also, it will be apparentthat this current materials-handling system which removes the slag inhuge chunks necessarily requires a multi-step process for recovery ofthe re-usable metal from the slag, with a considerable amount ofstepby-step handling, vwhereby the metal re-claiming system is lessefcient and more costly than desired.

Referring now to FIGURES l-ll, the new improvedslag-removal-andametal-recovery system of the present invention will nowbe described.

Referring especially to FIGURES l and 2, in this new system, thefront-llush slag 64 is discharged through a short rectangular chute 66ain the charging oor 24 into an inclined trough-shaped front-flush slagrunner or chute 7S, which extends through an aperture 25 in verticalwall 27 and is suspended from the underside of the charging door 24 bysuitable means generally indicated at Si) in FIGURE 2 (and hereinafteramplified with reference to FIGURES 9 and 1G). The front-flush slagspills from the lower end of the runner or chute 78 into one end of agranulator generally indicated at 82, which is located at yard level inthe kitchen 26, and is fully described below.

ln the embodiment illustrated in FIGURE 2, the slag spout 58 on thesteel ladle '513 is disposed with its axis substantially perpendicularto the longitudinal axis of the ,furnace 2t? and substantially in linewith the center door front-flush trough 62. The quite hot andsubstantially viscous ladle slag 67 is discharged from the spout 58 toan inclined trough-shaped runner or chute 79, whose lowermost endoverhangs the end of granulator 82 which is nearer the furnace. ladleslag runner 79 extends over the upper end of the slag grade or hill 72formed by dirt or debris within the pit 68 under the furnace Ztl, andalso extends through a suitable aperture 31 in the Vertical wall 27, asillustrated in FIGURE 2. If the ladle slag chute is unitary it ismovably supported by suitable means, such as chain hoists on a monorail,indicated at `83 (and hereinafter amplified).

The ladle slag runner or chute 79 can also be made in two sections, asillustrated, including an upper trough-like section 79a of smallercross-sectional size land a lower section 78h of slightly langercross-sectional size, whereby the lower end of upper runner section 71amay removably nest in the upper trough-shaped end of lower ruimersection 79h, with overlapping portions indicated Aat 79e in FIGURE 2.The upper ladle slag runner section 79a may ybe individually movablysupported by any suitable means, such as schematically indicated at 83in FIGURE 2 (and hereinafter amplified), as is 'also the lower runnersection 79b. Thisimakes it possible to remove runner section 79a fromladie slag run-olf position of FIGURE 2 to adjacent the underside of thefurnace for any desired purpose, without moving the part of the ladleslag runner which extends through aperture 31 in wall 27.

-It is noted that when the ladle slag is transported to a granulator inthe kitchen, as in the embodiment of FIG- URE 2, the wall 27 can be madeas a short retaining wall extending from yard level only the distancenecessary to support slag grade 72, thus providing greater access to,Iand more room for movement of, ladle slag runner 79 (or 79h).

Ladle slag discharge chute 79, or -a two-part chute 79a and 79h, may bemade in any suitable manner and of suitable material (c g., cast steelwhich may be lined with refractory), in a manner lwhich will be apparentto those skilled in the art in light of the disclosure herein. (Hence,more detailed disclosure of the chute per se than contained herein isdeemed unnecessary.)

Referring especially now to FIGURES 3-7, the slag granulator 82comprises a large rectangular tank which The lower portion of issomewhat boat-shaped, as is especially apparent from FIGURES 3 and 4. Inthe illustrated embodiment, the granulator tank 82 includes a frame workcomprising: a pair of angles 84 along the bottom longitudinal edges onopposite sides `of the tank; a pair of angles 86 along .the edges onopposite sides of the sloping tank bottom; a pair of angles 88 formingthe vertical end posts at the end of the tank near the furance (at theleft in FIGURES 3 and 4); a pair of angles 92 and 94 forming the lowerand upper edges of the same end of the tank; a pair lof angles 90forming the long sloping upper edges on 4opposite sides of the tank; anda plurality of angles 96, 98, and 104 extending between bottom sidesangles 484 and top side angles 90, on both sides of the tank (as isespecially apparent from FIGURE 3) to form supporting framing for thelonger tank sides. The tank of granulator 82 also comprises: ahorizontally disposed rectangular bottom plate 106; a sloping bottomrectangular plate 108; a pair of like plate side walls 110, each havinga configuration as shown in FIGURE 3 and a rectangular end wall 112(towards the furance). The aforementioned components are welded, orotherwise suitably secured together to form a water-tight granulatortank of boat-like shape, in a manner known in the art.

One tank side wall 110 (the one shown in FIGURE 3) is provided iwith arect-angular cutout 114 of suitable size to provide a weir 116 foroverflow of water in the tank, indicated at 117. The water ows from thetank of granulator 82 into a rectangular-shaped water discharge box 119,from which it is in turn carried away through ya discharge pipe 121 forsuitable disposal. (A discharge or recirculating pump may be provided inpipeline 121, if necessary or desired.) The top of the water dischargebox 119 is preferably open to permit water to overflow the -box in theevent there is some sort of stoppage in the discharge pipe 121. Anadditional angle 102 is provided on the granulator tank side 110 whichhas the aperture 114- forming weir 116, so that the water discharge box119 can be better supported between angles 162 and 104, as is especiallyapparent in FIGURE 3.

A suitable steel framework 120 is provided at the end of the granulatortank 82 nearest the furnace 211 to cradle the lower end of thefront-flush slag chute 78 and the lower end of the ladle slag dischargechute 79 (or 7%, if the latter is made in two parts). This chutesupporting framework 120 may comprise a pair of spa-ced channels 124suitably secured in vertical pos-ition to the rear of the tank ofgranulator 82, by welding or the like, with two horizontal channels 126and 12S suitably secured between vertical channels 124, so as to cradleand support the ends of slag spouts 78 and 79 which overhang the end ofthe granulator 82 adjacent the furnace.

The end wall 112 of granulator 82 is provided with a pair of rectangularapertures that receive the forward ends of nozzles 130, which Iare shownin detail in FIG- URES 5-7, to which reference is now made. Each of thenozzles 130 has a configuration which will be apparent from FIGURES 5-7,with the nozzle comprising: a pair of like side plates 1'33 of a shapeas shown; Ia pair' of top and bottom nozzle plates secured to the edgesof side plates l133; a pair of like trapezoidal-shape plates 137 securedto the edges of plates 135, `and also to a pair of like plates 141 whichare also secured to the ends of plates 133; and a rectangular ange plate143 secured to the rear edges of plates 137 yand 141. The plates 133,135, 137, 141 and 143 are preferably lwelded together to form the nozzle130. The end plate 143 is provided with `an annular aperture '143m andthere is welded to the plate 14.3, around the aperture 143e, a coupling143b which is adapted to have a conduit 131 connected thereto, for thefeeding of the cooling fluid, such as water, through the nozzles 130into the granulator tank 82. As will be noted from FIGURE 7, the insideforward edges of top and bottom nozzle plates 135 are milled at 135a toform a rectangular passageway 135b, so that the water will exit from thenozzle 130 in a at wide jet. There are welded to the sides 133 of thelnozzle 130 a pair of lugs 133a which have a plurality of apertures133-b whereby the nozzle 130 can be mounted on the granulator tank k82by bolting the same to any suitable support means (not shown for clearerillustration in the drawings), with the forward ends f the nozzle 130extending through the rectangular apertures in granulator Itank end wall112 as previously indicated.

Water is fed through the nozzles 130 from conduits 131 under substantialpressure, supplied by suitable commercially available pump means notshown, whereby the water is expelled from the rectangular openings 135bof each of nozzles 130 in a flat jet stream which spreads out somewhatin direction of the width of the granulator tank 82 near end wall 112.The hot slag which spills into the end of granulator tank 82 from thefront ush chute 7S (and the ladle slag chute 79 in the embodiment ofFIG- URE 2) intercepts these at streams of water from jet nozzles 130,thus causing the slag to be rapidly chilled and granulated. This resultsin the production of relatively iinely divided discrete pieces orparticles of solid metal, solid ferrous ore, non-ferrous slag andgangue. This granulation of the molten steel slag is achieved by acombination of mechanical disruption of the molten steel slag dischargedinto the granulator 82 and chilling of the slag by the water jet streamsfrom nozzles 13h (particularly the upper nozzle).

The granulator 82 is provided with an endless scraper or rake-type ightconveyor, which is generally indicated by the numeral 132 and shownespecially in FiGURES 3 and 4. This conveyor comprises a driven headshaft 134 which is mounted at each end in suitable bearings 136supported on the upper longitudinal edges of the granulator tank 82 atthe end nearer the furnace, with three toothed sprockets 13Snon-rotatably secured thereon. The bearings 136 are mounted on the sidesof the granulator tank S2 in any suitable manner, and preferably on apair of larger-sized angles l139` of suitable length which are securedto the upper tank-frame angles 91B in any suitable manner to providebetter supporting means for the bearings y1316.

A tail shaft 140 is provided with its ends rotatably mounted in suitablebearings 142 on the sides of granulator tank 82 adjacent its prow end,and has three tail shaft rollers 144 non-rotatably secured to shaft 140,one each being in longitudinal alignment with one of the toothedsprocket wheels 13S, as shown in FGURE 3. An endless link-belt log chain145 extends over each of the three sets of aligned sprockets 133 andtail rollers 144, with part of each chain being suspended near thebottom plates |106 and 108 of the granulator S2 as shown in FIG- URE 3.A suitable chain for this purpose is the C131 Link Belt logging chain,with F2 attachments which include Vportions for mounting of rectangularsteel flights `146. Each of the ights 145: is secured to an upstandingportion of three corresponding transversely aligned F2 attachments inchains 145 by machine bolts, thereby providing a plurality of dragflights extending substantially across the width of the granulator tank$2 at small spaced intervals on the chains 145. Since the constructionof such a C131 link belt logging chain with F2 attachments and flightsis known in the art, and the components can be obtained commercially,further detailed disclosure and discussion thereof is deemedunnecessary.

The lower sections ofthe chain flight conveyor 132 are located near thetank bottom plates `1116 and 198 so that the flights 146 will rake thegranulated slag and metal in granulator 32 to the upper prow end ofsloping bottom plate 1418.l The outer edges of the flights '146 slightlyclear the bottom tank plate 1116, thus Causing forma- Y tion of a smalllayer of granulated slag and metal particles on the tank bottom, whichin effect form a wear plate that minimizes abrasive wearing of bottomtank plate 166. Because the tank plate 108 slopes so that the granulatedparticles of metal and slag will tend to slide to the bottom of thetank, these particles are not relied on as a wear plate, but anadditional wear plate 109 is usually provided on the inside of plate 108for this purpose. The link chains 1415 and head and tail shafts 134 and140 are adjusted so that the outer ends of the flights 146 will slightlyclear this inside wear plate 1119. Two additional elongated wear plates11-1 are preferably also provided along the bottom inside of the maintank sides to reduce wear of large side walls 111) due to the abrasiveaction of granulated slag and metal particles moved along the tankbottom by flights `146` on chains 14S.

A plurality of return idler roller shafts 147 are suitably rotatablymounted across the open top of the granulator tank, with three rollers14S non-rotatably secured on each of shafts 147, to support at spacedpoints the upper stretch of each of log chains and flights 146. The endsof the return idler shafts I147 are rotatably mounted in any suitablebearing on a suitable support means 149. For example, support means `149may comprise a pair of spaced angles 151 extending transversely acrossthe top of the granulator tank 82, with their ends welded or otherwisesecured to upper tank edge angles 96; and short pieces of channel iron153 secured between angles 151 over angles 98 to provide brackets forthe bearings '14170 in which the ends of idler shafts 147 are rotatablymounted.

The flight chain conveyor 132 is driven in the direction indicated bythe arrows in FIGURE 3 by a variablespeed electric motor 151), which issuitably supported on or adjacent the granulator 82 and drivinglyconnected to the conveyor drive shaft 1134 by suitable means such as abelt 154 driving pulley 152 on shaft 134.

It will be noted that the slag can be discharged from the chute 78 (andchute 79, per FIGURE 2) into the water in granulator 812 through theflights 14e of the rake conveyor 142. Thus, continuous conveyoroperation does not interfere with the discharge of the slag from theopen hearth furnace into granulator 82, especially during the periods ofmaximum front slag flush when the slag may be thrown forward from theend of chute 7S as it spills into granulator 82.

As shown in F-'GURE 3, one side wall 11i) of granulator S2 is providedwith a plurality of apertures 156, 153, 16@ and 162, above the waterline 117 (which is determined by the loc-ation of weir opening 114 andthe quantity of water and granulated slag and metal in the granulator82). A manifold 164, which has a configuration substantially as shown inFIGURES 4 `and. ,5, is mounted on the side of the granulator 82 bysuitable support means (not shown to permit clearer illustration ofother parts); and manifold 164 includes lateral ducts 166, 168, 17) and172 whose ends are suitably secured by a conventional gas-tightarrangement to the granulator side wall 11) around the apertures 156,153, 16) and 15,2, respectively. Generally, the apertures 156, 158, 151)and 162, and their related manifold ducts 165, 168, 17@ and 172, willprogressively decrease in size as they are located nearer the prow endof the granulator tank 82, because less steam will have to be removed atthe latter end than at the slag input end.

A pipe 174, including a convention-al venturi 176, is suitably connectedto -an aperture in the rearward elbow of the manifold 164; and'there isin turn coupled to this an air hose 178 for supplying air to theelongated main section of manifold 154. As will be apparent, thegranulation of hot slag spilling from the chtite 7?; (and 79) into thewater jets from nozzles 131? in granulator tank 82 may cause asubstantial quantity of steam to be generated, and this must be removedfrom the kitchen 26 where the granulator S2 is located. Accordingly,during this granulating operation, air is supplied at a suitablepressure to the manifold 164 from the venturi inlet pipe 174, 176, andthis creates an aspirator effect which lowers the pressure in mani-foldducts 166, 168, 170 and 172, whereby the steam exits from the tank ofgranulator 82 through side apertures 156, 158, 160 and 162 into the mainconduit of the manifold 164. The steam is then conducted throughsuitable conduits for disposal, as, for example, by venting toatmosphere through an opening in furnace building wall 22. If necessaryor desired, an exhaust-fan arrangement capable of handling steam can besupplied at the vent in building wall 22 or elsewhere in the steamconduit system connected to steam manifold 164 to assure adequateremoval of steam, in light of such factors as quantity of steam, size ofconduits, distance to venting, etc. As the particular construction ofthe steam discharge system is not per se a feature of the presentinvention, and suitable arrangements will be apparent to those skilledin the art in light of this disclosure, further extended discussionthereof is believed unnecessary.

In addition, to avoid having steam generated within the granulator tank82 pass off into the kitchen 26 in objectionable quantities, thegranulator 82 is preferably also provided with a suitable hood generallyindicated at 180 in FIGURES 2 and 3. As illustrated, steam hood 180comprises a suitable rectangular box-like framework, made up of pipe orwood members indicated at 182; and the upper part on sides of framework182 is covered with a suitable material 184, such as heavy canvas, forpreventing excessive egress of steam from the granulator 82 into kitchen26. As illustrated in FIGURES 3 and 4, the steam hood 180 is supportedover the tank of granulator 82 with one end spaced a sufiicient distancefrom granulator end wall 112 so that the slag discharged into thegranulator 82 from the chute 78 (and 79) does not spray the steam hood180; and the other end of hood 180 is adjacent the prow end of thegranulator 82. The steam hood 180 is supported in desired relation tothe granulator 82, slightly clearing the top of conveyor ights 146 byany suitable means; preferably this is done by a plurality of chains orcables 186 secured at their upper ends to the Ceiling of the kitchen 26,and at their lower ends to the steam-hood framework 182, as illustratedin FIGURES 2-4 of the drawings, whereby the steam hood 180 will floatabove the granulator, thus preventing rupture of the hood walls 184tbyexcessive steam. If desired, the steam hood 180 may be suspended from I'the ceiling of kit-chen 26 by suitable conventional hoist means so thatit can be c-onveniently raised to provide access to the parts ofgranulator 82 below the hood.

Operation of the rake conveyor 132 during the granulation of slag in thegranulator 82, as previously discussed, causes the resultant granulatedparticles of metal and slag to be dragged along tank bottom 106 andsloping plate 108 `by flights 146 so that the granulated mixture isultimately discharged from granulator 82 to an inclined chute 188mounted at the upper prow end of the granulator (by any suitable supportmeans not shown for clearer illustration of other parts in thedrawings). The granulated mixture of slag and metal particles thenspills fr-om Chute 183 onto an endless moving Conveyor belt 190, whichis of commercially available conventional type (and therefore is showndiagrammatically in the drawings, FIGURES 1 through 4). Referring nowespecially to FIGURE 1, the conveyor 190 transports the granulatedrelatively small particles of slag and metal, indicated by the numeral192, out of the furnace building 22 through a suitably located aperture194. In the illustrated embodiment, the conveyor 190 transporting themixture of granulated slag and metal from granulator 82 discharges thismixture 192 onto an endless belt conveyor 196, which runs along theoutside of the building and is ad-apted to receive the discharge ofmetal and slag mixture 192 from each of the granulators 82 servicingeach of the open hearth furnaces 20, as shown for two furnaces in FIGUREl.

The endless belt conveyor 196 conveys the granulated mixture of metaland slag 192 to a continuously operating variable fieldmagnetic-separator arrangement which is generally indicated at 198 inFIGURE l and diagrammatically shown in FIGURE 9, to which reference isnow made. The end pulley 200 of the main conveyor belt 196 carrying theslag-and-metal-particle mixture 192 is magnetic; and there is disposedadjacent and substantially parallel to the magnetic pulley 200 asplitter 202 having a configuration and position as illustrated inFIGURE 8. As the particles of slag and metal mixture 192 on the conveyorbeit 196 pass over the magnetic pulley 200, the magnetic ferrousparticles, indicated at 1925i, adhere to the belt 196 to suliicientextent so that they fall to the side 202a of the splitter bar 202, andthence onto another conveyor belt 204 which carries these magneticparticles to a suitable disposal point for ultimate re-use in thefurnace. The non-magnetic particles, indicated by the numeral 192b, donot adhere to the magnetic end pulley 200 and are in effect thrown overto the other side 202b of the splitter bar 202, and thence onto anotherendless conveyor 206 which carries these non-ferrous particles off to asuitable dump, as diagrammatically shown in FIG- URE 1. Theconveyor-and-magnetic-separator means 198 is known and its componentsare commercially available and the particular construction ofconveyor-andseparator means 198 does not per se form a part of thepresent invention, so that further discussion thereof is believedunnecessary. As shown in FIGURE 1, the ferrous material which has beenthus magnetically separated from the non-ferrous slag may be transferredby conveyor 201i directly to a suitable hopper 208, from which theferrous material may be loaded onto trucks 76a for transport to the openhearth furnace building for re-use when desired.

While FIGURES l and 8 illustrate a preferred system for continuouslytransporting granulated slag and metal from the several granulators 82in the furnace building 22, with a conveyor-and-magnetic-separatorsystem for separating the ferrous material from the non-ferrous slag ina continuous operation, it will be understood that the granulatedmixtures of metal and slag from granulators 82 can be discharged fromthe associated conveyors 190 to some other suitable transport means,such as box cars on rail spurs along the side of the furnace building22, hydraulic pipeline transportation, etc.4 The particular means forconveying the granulated mixture of metal and slag from the respectivefurnace granulators and out of the plant building 22 will depend on theopen hearth plant layout and geography and location of other millinstallation. Suitable modifications of the preferred arrangement shownin FIGURE 1, according to such factors will be appa-rent to thoseskilled in the art, in light of the disclosure herein.

Referring back to FIGURE 2, as has been previously mentioned, thefront-flush slag conveyor 78 is movable by hoist means generallyindicated at 80|, for reasons that will now be amplified together with amore detailed description of slag chute moving means 80 which isdisclosed in more detail in FIGURES 9 and l0 to which reference is nowmade.

As shown particularly in FIGURE 10, the front-flush slag chute 78comprises an elongated runner and boot section 78 and an enlarged headend 78 with a configuration as illustrated. The chute 78 is made of caststeel, with a radius on all angles to facilitate free flow of the slagin the chute, which may also be lined with a suitable refractorymaterial if desired. Each side of the chute 78 is provided with a pairof lugs 99 near the boot end of the chute and 99 near the head end ofthe chute. Boot end lugs 99 are attached to a cable or chain 85, andhead end lugs 99 are connected to a cable or chain 87, with the boot endcable or chain being part of a hoist 89 and the head end cable or chain87 being part of a hoist 91. Chain hoists 89 and 91 are mounted ontrucks 93 and 95, which are in turn movably mounted on a monorail 97suspended from the ceiling of the kitchen 26 in any suitable manner, asdiagrammatically illustrated in FIGURE 9.

As will be apparent from FIGURES 9-10 (and FIG- URE 2), the head end 78of chute 7S extends through aperture 25 in the upper part of thevertical wall 27 which separates the kitchen 26 from the pit 63 belowthe furnace and, if desired, the underside of the chute 78 can becradled on the bottom portion a of this wall aperture. A four-sidedrectangular steel spillway 66a is suitably mounted in front of thecenter charging door Il() and below the front-flush trough 62. Thus,when the frontllush slag chute 78 is in normal position A shown in solidline in FIGURE 9, with its boot end extending over the input end of thegranulator 82 (which is only diagrammatically shown in FIGURE 9), theslag 64 flushed from the front of furnace 29 is discharged through thespillway 66a into the head end '78 of chute 73. rIhre slag then willpass down the chute 78, which is generally at an angle of about fromhorizontal, and spill from the boot end 7S into the granulator 82 whereit is converted to granular particles of slag and metal, as previouslyexplained. If, for some reason, it is desired not to use the slaggranulator 82, the head end 78 of the chute 73 is raised by hoist 91 andcable $7 to the dotted line position B in FIGURE 9, whereby chute headend 78" is removed from the path of the front-hushed slag, which isdetermined by the spillway 66a; the boot end 78 of the chute 78 is alsoraised by the hoist $9 and cable S5 so that the chtite is then in thedotted-line position C in FIGURE 9, with its head end 7S still clear ofthe frontflush slag spillway. Then the slag chute 78 is removed awayfrom the furnace, if desired or necessary, by movement of hoist trucks93 and 95 along monorail 97, which can be done by suitable remotelyoperated motor and 'i control means. The size of the chute 78, thelocation of hoist cable chute lugs 99 and 99', the normal location ofthe hoist means 87, 89, 91 and 93 can be predetermined with respect tothe spillway 66a by kinematics, so that the chute 78 will travel anappropriate path for withdrawal from itsnormal position for conveyingfront-flush slag to the granulator S2. This arrangement makes itpossible to promptly-divert molten front-flush slag (or steel) 64 to theslag grade 72 and the pit 68 below furnace Ztl, for removal by currentpractices described above, when necessary or desirable; e.g., in thecase of a furnace reaction or break out there would be a sudden increaseof load on the granulator S2 which could create a dangerous condition ifthe surge of molten slag (and/ or steel) were not diverted.

Suitable hoist and monorail trucks means, such as diagramaticallyindicated Vat 85, 87, S9, 91, 93, 95 and 97 are commercially available,and arrangements for employing them in a system according to FIGURE 9will be apparent to those skilled in the art in light of the presentdisclosure, so that a more-detailed showing and discussion Vthereof isbelieved unnecessary, especially since the particular details of thesechute hoist means are not per se a part of the present invention.

Referring again to FIGURE 10 the kitchen side of wall 27 may be providedwith a steel door 101 mounted in suitable vertical slideways 103 on eachside of wall aper- :ture 25, with cables 105 attached to said door 101and -operated by motor-driven hoist means (not shown). Thus, when thefront-flush granulator slag runner '78 is `withdrawn from below spillway66a to divert front-flush slag to the slag grade 72 in pit 68 below thefurnace, the door 101 can be also raised to cover opening 25 in wall 27to prevent any front-flushed slag from spraying into the kitchen 26.

kReferring back to FIGURE 2, the hoist means 83 for moving the uppersection 79a of the ladle slag chute 79 in this embodiment may be likethe above-described front-flush slag chute hoist means 843. Accordingly,a suitable construction for hoist means 83 will be apparent to thoseskilled in the art and further discusison thereof is believedunnecessary. It is also noted, however, that hoist means 83 for theupper ladle slag chute portion 79a could comprise a single hoist andchain connected to lugs on the opposite sides of the chute section 79aso as to cause that chute section to pivot around its lower end which isnested in the upper end of lower chute portion 79h (i.e., in the regionindicated by numeral 79e inV FIG- GURE 2). Such arrangements permitwithdrawal of the ladle slag chute of the FIGURE 3 embodiment fromadjacent the steel ladle 50, if and when desired.

Another preferred embodiment for granulation of open hearth steelfurnace front-flush slag according to the present invention with apreferred movable-chute arrangement for transferring molten slag to agranulator (like 82) in the kitchen 26 away from below the charging doorspillway 66 and promptly diverting the molten slag from the granulatorto below the furnace, when desired, is disclosed in my copendingapplication Ser. No. 304,932 on i Steel Slag Handling System, filed Aug.27, 1963, as a continuation-impart of my aforementioned patentapplication Ser. No. 126,792, tiled June 28, 1961; and the disclosure`of my said application Ser. No. 304,932 is incorporated herein byreference as though fully set forth herein (said application Ser. No.304,932 has been abandoned in favor of copending application Ser. No.551,168 on Steel Slag Handling System led May 18,` 1966).

Referring to FIGURE 11, there is shown a modification of the newimproved slag-removal system of this invention described above withreference to FIGURE 2, in that the arrangement for granulating andhandling the steel ladle slag differs from the arrangement shown inFIGURE 2f.

More specifically, the slag-removal system of FIGURE 11 is the same asthat described with reference to FIG- URES 1-10, excepting that theladle slag discharge chute 79 shown in FIGURE 2 isfomitted together withrelated parts such as apertures 31 in the wall 27, the cradle 128 ongranulator 82 for the boot end of the ladle slag removal chute 79, thehoist means 83, etc.

In lieu of the steel ladle slag removal chute 79, etc., in the system ofFIGURE 2, the system of FIGURE 11 includes another granulator g2b on thepit side Z8 of the furnace building for granulating slag discharged fromthe steel ladles Si) of the various open hearth furnaces 20. Thegranulator S212 is of the same construction as the granulator b2 in thekitchen 26 described above with particular reference to FIGURES 3-7, butis of a smaller size since the ladle slag comprises about 35% of thetotal slag per ieat, whereas the front-hush slag comprises about Forconvenience, major comparable parts of the ladle slag granulator 82h areidentified in FIGURE 11 by like numerals as corresponding parts ofgranulator 82 in FIGURES 3-7 plus the letter b; and detailed descrip-Vtion thereof is believed unnecessary, since the mode of operation ofgranulator '82.19 is the same as that of granulator 82 installed inkitchen 2e to handle the front-flush slag in this system (as in that ofFIGURE 2).

The steel ladle slag is discharged into a separate granulator 2!) on thepit side of the furnace room, while the front-flush slag is beinghandled by a granulator 82 in the kitchen of the furnace room, asdescribed above. More particularly, in this embodiment, the slag spoutSS on each steel ladle Stb is aligned with the tap hole of the furnaceZtl, but extends from the ladle 5ft on the side away from the furnace2G, whereby the steel ladle slag overflows into a slag chtite 79f fromwhich it spills into the jet stream end of granulator 32h, which is likethe granulator S2 of FIGURES 2 and 3, but is of smaller size and issuitably mounted on a rail car of conventional construction, in a mannerthat will be apparent to those skilled in the art. The granulator 82hcan be moved along rails 212 on the pit oor, running :parallel to theline of the furnaces 2b, so that the granulator 82h can be positionedwith chute '79e at the particular steel ladle 5t) for the furnace beingtapped. The chute 797c can be supported between the steel ladle slagspout 58 and the jet-stream end of the granulator 821; in any suitablemanner; one suitable system is to mount the chute 79]c on a chain orcable hoist that is movable on an overhead monorail along the length ofthe furnace parallel to the track 211 for convenient removal from ladle50 and transfer of chute 79f along with the granulator 82h to the nextsteel ladle to be tapped. The conveyor means 190b which receives thegranulated mixture of slag and metal particles (19211) from the chute18811 at the prow discharge end of the granulator 82b is set up, in amanner known in the art, so that conveyor 19017 can be moved to behindeach of the various furnaces 20 in the open hearth plant, for suitableremoval from the furnace building of the ladle slag granulated in thegranulator 82b. The steam hood 18% is suitably mounted on the granulatorg2b, and a suitable steam-removal arrangement, water input means, andair input means are provided for granulator 82h to permit mobility.

While it is believed that the operation of the new improved slag-removalsystem of the present invention Will be apparent from the foregoingdescription thereof with reference to FlGURES l through 11 (and l2) themode of operation of the system will be briefly summarized: During thesteel-making operation of the open hearth furnace, about 65% of the slagis front flushed through the trough 62 cut in the refractory frontfurnace wall 30 below the center front furnace door 40 into the spillway66a, whence this hot molten slag falls into the head end of thefrontsush slag chute 73. rl`he hot slag then spills into the rear end ofthe granulator 82, and intercepts the two horizontally extending jets ofwater emitted from the upper and lower nozzles 130. The molten slag isbroken up by force of the jets and rapidly chilled by the water jetstreams in the air above the level of water bath 117 in granulator 82,thus converting the slag into a relatively finely divided granulatedsolid product which consists of discrete particles of solid metal andsolid slag, with the metal particles being substantially free ofadhering slag, so that the metal and slag particles may later be readilyseparated. The granulated particles of slag and metal fall into thewater bath 117 in the bottom of the tank of granulator 82, where theyare further cooled. Particles of slag which are still sufficiently hotmay be further granulated to some extent in water bath 117, particularlyin conjunction with the action of rake conveyor 132 which moves theresultant granulated particles of metal and slag falling to the bottomof the granulator tank so as to discharge the granulated slag from theupper prow end of granulator 82 to a transport means such as chute 188and associated continuous belt conveyor 190.

The rake conveyor 132 within granulator S2 is an advantageous feature ofthe steel-slag granulation system of this invention because: (a) Theflights 146 of the rake conveyor 132 moving granulated slag through thewater bath 117 below the level determined by Weir 116 agitate the waterbath, thereby preventing the accumulation of steam and/or gas pockets byreason of slag being insuiiiciently cooled when it falls into the bath117, thus avoiding explosions. (b) Flights 146 of rake conveyor 132 alsotend to break up any relatively large pieces of slag falling into waterbath 117, facilitating granulation and cooling thereof. (c) The rakeconveyor 132 continually moves the granulated slag away from water jetnozzles 130, preventing the accumulation and pileup of slag in front ofthe nozzles 130 (which may otherwise occur, particularly at a high rateof slag tonnage feed to the granulator 82), and also preventing thebuild-up of any hot spots in accumulated slag pileups. (d) The rakeconveyor 132 promptly removes the granulated slag from the water bath117, and as the slag moves up the slope 103 of the prow end ofgranulator 82, the slag is further cooled in the air, and steam and/orgas can readily escape to the atmosphere. (e) The rake con veyor 132continuously and rapidly positively displaces and removes large tonnagesof granulated steel slag, even as it is being discharged from thefurnace, whereby large slag tonnages from a modern steel furnace can behandled by a rather small granulator which can be installed near thefurnace in the limited space available in existing steel furnacebuildings (e.g., an open hearth kitchen), without interfering withnormal steel-making 'practice Hence, this rake-oonveyor arrangement ingranulator 82 provides a safe, practical, commercially `usable system,although other equivalent means may be provided to achieve such mode ofoperation and results. Steam formed during the granulating of the slagis carried olf from granulator 82 through manifold 164 and relatedconduits due to the air input from pipe 174, and is ultimately vented toatmosphere; and hood 186 prevents undue spread of steam in kitchen 26.

Conveyor 199 carries the granulated slag from the furnace building 22(according to the lay-out of the furnace plant). Preferably, theplurality of granulators 82 in the kitchen of the open hearth plantdischarge the granulated slag and metal to a common conveying andmagnetic separator means for continuously separating the ferrous andslag particles and transferring them to suitable disposal points (as inthe embodiment illustrated in FIGURE l). When the furnace is tapped, theremaining 35% of the melt slag discharged to the top of steel ladle 5t)after the tapping of the steel is also fed to a granulator whichconverts this slag to relatively small discrete particles of metal andslag, in like manner as the front-flush slag. As disclosed above, thesteel ladle discharge slag may be transferred to the kitchen side of thefurnace for granulation in the same unit 32 which granulates thefront-flush slag, and subsequent removal from the furnace building 22 bythe same conveyor system 19t). Or, if this is not suitable for a givenopen hearth furnace installation, the steel ladle slag may be granulatedin another granulator on the pit side of the furnace, and the resultantmixture of metal and slag particles carried away from the furnace andout of the furnace building by another associated conveyor means, forlater separation of the ferrous metal from non-ferrous slag (asillustrated and described with reference 'to FIGURE l1). The waterdischarged from the granulator 82 to conduit 121 may be disposed of orrecycled for reuse in the granulator (preferably after removing solidstherefrom by settling or the like).

Factors which are relevant to use of this new improved slaggranulating-and-removal method and apparatus and determine theparticular size and design of the equipment involved, include thefollowing:

(a) temperature of slag discharged from the furnace (front-flush slag,and ladle slag, respectively);

(b) quantity of front-Hush and ladle slag discharged per minute into thegranulator, especially at maximum rate;

(c) the pitch of the chute(s) conveying the slag from the furnace to thegranulator (and slag viscosity);

(d) the size, shape and location of the granulator jet nozzles inrelation to such factors as the over-all size of the granulator,quantity of slag handled, especially at maximum rate, etc.;

(e) the input water pressure to the granulator jets;

(f) the ratio of water input to slag input for a given time period;

(g) the input water temperature; and

(h) the quantity of steam generated, and capacity of the steam-removalfacilities provided.

By way of example, water ejection nozzles (shown in FIGURES 5-7) mayhave a rectangular jet aperture i) of about 14 inches by 1% inch incrossasection, for a granulator 82 (shown in FIGURES 3 and 4). Thegranulator 82 is about 321/3 feet long (the flat bottom being about 2Ofeet long), about 5 feet high at the jet and 71/2 feet high at the prowend, and about 51/2 feet wide; and the upper land lower nozzles 130 arerespectively located about one foot and 1% feet from the upper edge ofthe tank end wall 112. Water is fed to nozzles 130 at sucient pressure,e.g., 35-60 p.s.i., and in sufficient amount, to produce substantiallyinstanteous solidification and granulation of the slag into metal andnonmetal particles of sizes running less than 1/2 inch in dimension,with the slag particles being friable and readily crushed or ground.

Water or a liquid of comparable characteristics must be used as theliquid for the jet stream and cooling7 medium to granulate molten steelslag in granulator 82 according to the system herein disclosed. However,because of its availability in large quantity at low cost, water is theonly presently known liquid which Ais commercially usable for the s-teelslag granulation system of this invention.

For convenience, the granulation system of FIGURES 1-10 may beconsidered as having three mutually perpendicular reference axes,indicated at x, y and z in FIG- URES 3 and 4 (and also in FIGURES 5-7).In the illustrated embodiment, the length of granulator 82 extends inthe direction of horizontal axis x (FIGURES 3 and 4), with side wall andother components extending in the direction of vertical axis y (FIGURE3), and with side wall and other components extending vertically asindicated at y in FIGURE 3, and with other components extendingtransversely to the granulators longitudinal axis x as indicated at z inFIGURE 4. Referring to FIGURES 5-7 wherein x, y and z axes per FIGURES 3and 4, are shown for convenient reference, each water jet nozzle 130 isprovided with a `tlat rectangular machined opening 135i) formed bymachined plate sections 13561 and vertically disposed side plates 133which extend in the direction of the granulator longitudinal axis x sothat a flat wide water jet is emitted horizontally from nozzle 130 inthe direction of axis x. It has been found that the width of therectangular aperture 135]) of nozzle 130, in the direction ofgranulators transverse axis z, should preferably exceed by at least thewidth between the inside of the side walls 211 of the end portion of theslag chute (see w in FIGURE l0) from which the molten steel slag ispoured into the water jet of granulator 82, when the centerline of saidend portion of the slag chute overlies the centerline of each water jetnozzle 130, as illustrated. If, however, the chute and nozzles do nothave their centerlines so aligned, then the width of nozzle opening135i) and the width w of the end portion of the slag chute a-tgranulator S2 should be such that each slag chute -side wall 211 islocated in transverse direction z So that each side wall 133 of waternozzle 130 is `disposed outside or beyond the respective chute wall 211a distance equal to at least 5% of the chute width. Slag chute end 78'should not extend any substantial extent in the direction of theItransverse horizontal z axis, to avoid feeding molten slag with anysubstantial trajectory in the direction of axis z transverse to thewater jet stream injected in direction of axis x. Thus, the slag chute78 should extend in the direction of the longitudinal axis x when slagis being poured into the granulator 82, as shown in FIGURES 1-4, 9 and11, and also as shown in FIGURES 1-3 of my aforesaid copendingapplication Ser. No. 304,932, incorporated herein by reference (saidFIGURES 1-3 showing the chute in granulation operating position for thelatter embodiment). Also, it is found desirable to make the slag chuteend portion 7S feeding the granulator 82 with substantially parallelside walls 211 extending for a sumcient length in the direction of thelongitudinal reference axis x to assure a proper molten slag trajectorywith reference to the water jet streams from nozzles 130. (That is, itis preferable not to use a slag chute whose end portions adjacentgranulator end wall 112 have non-parallel side walls extending in thedirection of transverse reference axis z at a substantial 20v angle tohorizontal reference axis x.) However, the nozzles 130 may be tiltedslightly up or down in direction of vertical reference axis y, so as tobe at a slight angle to horizontal reference axis x.

It has been found that to achieve eicient magnetic separation ofcommercially usable ferrous material from steel slag granulated with thenew steel granulation system of this invention, using commerciallyavailable magnetic separation equipment (such as sold by StearnsMagnetic Division of Indiana General Corp), the size of the granulatedsteel slag particles should be 1t-inch in size or smaller. In fact, thegranulated slag particles preferably should be minus 35 mesh (Tylerstandard screen), which is minus 0.0164 inch; and in any event or moreof the granulated slag particles should be minus 10 mesh (Tyler), whichis minus 0.065 inch.

In some plants, it is desirable to use a hydraulic slurry pipe andpumping system for transport of granulated slag and metal from thegranulator 82 at the furnace to remove it from the furnace building to adisposal site. For such a hydraulic transport system the granulator 82should be operated to produce resultant granulated steel slag of minus1A inch, although a hydraulic slurry transport system with a largeenough pump would handle particle sizes up to 2 inches (larger particlesbeing mechanically removed between the point of discharge fromgranulator 32 and the pump). However, from the viewpoint of safe eicientgranulation of steel slag, more ecient separation of usable ferrousmaterial, `and more etlicient trouble-free hydraulic transportation, 90%or more of the granulated slag particles should be minus 1A inch, andpreferably of mesh size per -the immediately preceding paragraph hereof.

To achieve a commercially desirable steel-slag handling system, itshould not only safely, continuously, and rapidly granulate and removelarge tonnages of molten steel slag, `but should also meet steel-milloperating rc quirements such as minimal water consumption, minimalsteam, control of particle size for economical magnetic separation,ready adaptability to varying slag tonnage disposal rates, reliable andefhcient hydraulic slurry transportation, trouble-free operation bysemi-skilled workers, etc. From operation of a steel-slag granulationsystem such as disclosed herein, it has been found that the steel slaggranulation system according to this invention s'hould preferably beoperated according to the following conditions:

(1) Water should be supplied to appropriately sized granulator nozzle(s)130 and associated water conduit(s) 131 in such quantity that the at jetstream of water is injected into granulator 82 from nozzle(s) 130 at ajet velocity in feet per second (fps.) and in gallons per minute (gpm.)varying in relation to the rate at which molten steel furnace slag ispoured into gran-ulator 82 to intercept the water jet stream(s), asfollows: (a) For a molten slag input rate of up to about 2 tons perminute, at least one dat water jet stream at a jet velocity of at leastabout 25.0 f.p.s. and at least about 400 gpm. (b) For a molten slaginput rate of 2 tons to about 4 tons per minute, at least one flat waterjet stream at a jet velocity of at least about 30y to V36.5 f.p.s. andat least about 500-600 g.p.m. (c) For a molten slag input rate of 4 toabout 7 tons per minute, inject at least about 1200-1800 gpm., either bytwo flat water jet streams through two nozzles, one over the other, eachwater stream having a jet velocity of at least about 36.5 to 55 fps.; orthrough one flat water jet stream via one nozzle fwith a jet velocity ofat least about 73 to 110 f.p.s. (d) For a molten slag input rate of over7 tons per minute, e.g., 7-8, inject at least 1800-2000 gpm., either bytWo flat Water jet streams through two nozzles, one over the other, eachwater stream having a jet velocity of at least 55 t-o 61 f.p.s., orthrough one flat water jet stream via one nozzle With a jet velocity ofat least about to 122 f.p.s.

(2) Water should be introduced to granulator 82 at a quantitative ratein gallons per minute varying in relation to the rate at which moltensteel furnace slag is poured into the granulator 32 as follows: (a)Water should be introduced into granulator 32 at the slag input end(adjacent wall 112) at an average rate of at least about 400 gpm. perton of steel slag per minute poured into the granulator. (b) However,water should preferably be introduced at the slag input end of thegranulator 82 at an average rate of about 900-1350 gpm. per ton of steelslag per minute poured into the granulator. (c) And, it is best to useat least about 1350-1600 g.p.m. per ton of steel slag per minute pouredinto the granulator to avoid objectionable vaporization and formation ofsteam. The input water preferably should be at typical Water-maintemperature (e.g., 60 to 70 E); however, furnace-cooling water or otherplant-used water may be employed, but its temperature preferably shouldnot exceed 100 F.

(3) It is preferable that the amount of water per paragraph 2 beintroduced into granulator 82 by means of the jet nozzles 130 in suchquantitative gpm. rates according to varying molten steel slag tonnageinput rates. However, in the disclosed embodiment of FIG- URES 2-7, thesize of the disclosed jet nozzles 130 is such that desired water jetvelocities and g.p.m per parts (a), (b), (c) and (d) of paragraph 1above frequently can be achieved with a lower quantity of water throughthe nozzle(s) 130 than required to meet the conditions of part (a), (b)or (c) of paragraph 2. In such event, it is possible to introduce therequisite water per paragraph 1 through the jet nozzle(s) 130 to achieveat least the water jet velocities and gpm. set forth in paragraph 1above, and to introduce the remainder of the water per paragraph 2 byother means; eg., a water pipe of suitable size may be secured to endwall 112 of granulator 32 below the lowest nozzle 130, at point 220 or222 in FIGURE 3, to supply additional Water to granulator h2 by conduitfrom a suitable suorce. However, the safest and best approach is tointroduce all water requirements per paragraph 2 into granulator 82through the `water jet nozzle(s) 130. This increases the eti'ectivenessof the water jets for breaking down the moltensteel slag into smallparticles to achieve more rapid and more eliicient slag cooling andgranulation, and helps assure smaller resultant granulated slagparticles for better magnetic separation and also more efficienthydraulic slurry transportation (in those shops 'where it is preferableto a conveyonbelt system).

(4) In light of the foregoing, good results can be achieved by operatingthe granulator system of this invention using two flat jet streams ofwater injected horizontally into granulator S2 through two like-sizenozzles 130, one over the other7 according to the following: (a) Formolten slag input of up to about 2 tons per minute, inject two waterstreams with jet velocity of about 36.5 to 61 f.p.s., and about1200-2000 gpm. through both jets. (b) For a molten slag input rate of 2to about 4 tons per minute, inject two water jet streams at a velocityof at least 61 to 122 f.p.s., and about 2000-400'0 gpm. through 'bothjets. (c) For a molten slag input rate of 4 to about 7 tons per minute,inject two water jet streams at a velocity of at least about 91 to 146f.p.s., and about 3000-5000 gpm. through both nozzles.

Granulation of the molten steel slag is generally largely accomplishedby the flat water jet stream from the upper nozzle 130, with the lowerwater jet stream from lower nozzle 130 supplementing the upper jetstream and also providing a safeguard against malfunction of the upperwater jet while molten steel slag is being poured. Thus, more effectivegranulation of the molten steel slag may be achieved by injecting Vs to3A (6U-75%), and preferably :Vs (66.6%), of available water through theupper of two like-size nozzles 130 (14 X opening, one over the other,aligned), and injecting the balance of the water through the lowernozzle. Thus, in light of the foregoing, goo-d results can be achievedaccording to the following: (a) For a molten slag input rate of up toabout 2 tons per minute and using water available at about 1200-2000gpm., inject about 80041350 gpm. (2/3) through the upper nozzle 130 atabout 49 to 82 f.p.s., and about 400-650 gpm. (1/3) through the lowernozzle at about 25 to 39.5 f.p.s. (b) For a molten slag input rate of 2to about 4 tons per minute and using water available at about 200G-4000gpm., inject about 1350-2700 gpm. (2/3) through the upper nozzle 130 atabout 82 to 164 f ps., and about 650-1300 gpm, (/s) through the lowernozzle at about 39.5 to 79 f.p.s. (c) For a molten slag input rate of 4to about 7 tons per minute and using water available at 300D-5000 gpm.,inject about 2000-3350 gpm. (2/3) through the upper nozzle 130 at about122 to 202 f.p.s., and about 1000- 1650 gpm. (1/3) through the lowernozzle at a velocity of at least about 61 to 101 f.p.s.

Operation of granulator 82 per the foregoing, especially per theconditions of paragraphs 4 and 5, provides resultant granulated steelslag of desirable particle size for eicient magnetic separation offerrous material, and efficient hydraulic transportation per discussionabove (see column 19, lines 59-75 and column 20, lines 1-33 hereof).

The water may be supplied to one or both nozzles 130 through each ofconduits 131 by conventional pump means at suitable pressure and insuitable quantity to achieve the desired nozzle jet stream velocity andgpm. input per paragraph 1 above, the desired g.p.m. water input perparagraph 2 above, or the preferred jet velocities and gpm. perparagraph 4 or paragraph 5 above, according to varying rate of steelslag feed to the granulator with different size steel furnaces, in amanner which will be apparent to those skilled in the art in light ofthe disclosure herein and using known scientific and engineeringinformation.

By way of example, referring to operating conditions per paragraph 4above, with like nozzles 130 of granulator 82 having a rectangular jetaperture 135b of about 14 inches by 3A; inch in cross-section, and a41/2 inch I.D. section at 143b connected to conduit 131, water suppliedat 35 p.s.i. to each nozzle 130 may be injected into the granulator 32at about 68 fps., and about 1100 gpm. from each nozzle, and thus 2200gpm. from both, accordJ ing to the suggested operating conditions ofparagraph 4 above. As another example, if granulator 82 has largernozzles 130 having a rectangular aperture 130b of 22 inches by 3/s inchin cross-section (eg, for use with a slag chute 78 having a width w of20 inches) with a 41/2 inch LD. section at 14317 connected to conduit131, water supplied at 35 p.s.1'. may be injected into the granulator 32at about 75.5 fps., and about 1950 gpm, from each nozzle, and thus 3900gpm. from both, according to suggested operating conditions of paragraph4 above.

Referring to paragraph 5 above, the thickness of one or both nozzles 130may be modified to analogously use more than half of available water inthe jet stream from the upper nozzle and less than half in the lower jetstream. Thus, the opening 132b of upper nozzle 130 may have a thickness(in direction of axis y) greater than the thickness of opening 132b oflower nozzle 1330, both the upper and lower nozzles having an opening132b with like width in direction of reference axis z. For example, theupper nozzle 130 may have an opening 132];` of 14 inches by M6 inchwhile the lower nozzle 132b has an opening of 14 inches by 3%; inch.Thus, by way of example, for a molten slag input of up to 2 tons perminute and using 2000 gpm. available water, 1200 g.p.m. (60%) would beinjected through the top nozzle at 49 f.p.s. and 800 gpm. (40% throughthe lower nozzle at 49 f.p.s.

When high water jet stream velocities.` are used, it may be desirable tosuspend a series of chains across the path of the jet stream(s) tointercept the jets and reduce splash 23 and spray at prow end 108 ofgranulator 32. Thus, referring to FIGURES 3 and 4, a bar (not shown) maybe attached to the two top angles 90 on the two granulator side wallsM0, at a longitudinal location between vertical angles 100 and 102, andextending across the top of the granulator tank parallel to rakeconveyor shafts 147, below the upper portion of rake conveyor chain 145.A series of ordinary heavy-duty chains are secured and hang from thisbar at suitable intervals, eg., 2 inches apart (in the direction oftransverse axis z), with a length such that the end of each chainnormally extends slightly below the level of weir 116, and thus belowthe usual operating level of water bath 117.

Open hearth front-flush steel slag is typically discharged over a periodof about 30 to 75 minutes, at a varying rate of up to about 2 tons perminute; however, the discharge rate may be much higher in the case of afurnace reaction or a breakout The present invention provides aneffective system for rapid continuous granulation of front-flush slagadjacent the furnace and removal from the building while slaggranulation is in process. Further, location of granulator 82 away frombelow the frontflush spillway 66 with displaceable means fortransferring molten front-flush slag to the water jets of granulator 82or diverting itto beneath the furnace provide important operating andsafety advantages, as in the case of a major breakout or furnacereaction which also usually discharges a substantial quantity of moltensteel through charging floor spillway 66. Open hearth tap or ladle slagis generally discharged from the top of ladle 50 (see FIGURE l2) in arelatively short time in a large quantity (e.g., 20 tons in 3.5 to 4minutes); this can be granulated adjacent the furnace using the presentinvention. Large tonnages of OSM or BOF steel slag may also be quicklygranulated with the present invention using above-discussed operatingconditions.

It will be apparent from the foregoing that the present inventionprovides a new improved slag-removal system which departs from thematerials-handling concepts of the above-discussed current and earlierslagremoval systems, thereby avoiding their serious shortcomings byconverting the very hot slag discharged from the open hearth furnace torelatively small discrete particles of ferrous metal and non-ferrousslag at low temperature, which can then be readily transported from theopen hearth furnace building by continuous conveyor means; that thepresent invention provides such a new improved open hearth slag-removalsystem by which the granulated slag and `ferrous material can beconveyed directly to magnetic separating means for quick, efficient, andeconomi-cal separation of re-usable ferrous metal from lthe non-ferrousslag, and suitable disposal of each; and that the present invention iscapable of complete removal of large quantities of red-hot slag produced`in large-tonnage open hearth furnaces a very short time after thefurnace is tapped, whereby slag removal no longer constitutes abottleneck preventing -optimum use of presently known oxygen techniquesand shorter heat times in large-capacity open hearth furnaces; and thatthe present invention also achieves other important objects andadvantages as discussed earlier in this application.

Claim language definition-(1) The terms ferrous ma- Vterial(s) andferrous pieces (or particles) as used in the claims means material whichis usable in the making of iron or steel. (2) The ter-m water and/orliquid as used in the claims means water or an equivalent liquid havinglike characteristics, as distinguished from a gas or steam. (3)Recitation in the `claims of the x, y and z axis (or axes) refers to therespective horizontal reference axis x, the vertical axis y, and thetransverse horizontal axis z, as indicated at x, y, and z in thedrawings and discussed above.

The invention may be embodied in :other speci-tic forms withoutdepartingfrom the spi-rit or essential characteristics thereof. The presentembodiments are therefore 24. to be considered in all respects asillustrative and not restrictive, the scope of 4the invention beingindicated by the appended claims rather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States LettersPatent is:

1. A method of handling molten steel slag characterized in that itcomprises: pouring -molten steel slag into a receptacle; injecting atleast one jet stream of water into said receptacle so as to interceptsaid molten steel slag to granulate the molten slag into particles; thewater stream being injected with a jet velocity of at least about 25.0f.p.s. and at least about 400 g.p.m. for a mol-ten slag input rate of upto about 2 tons per minute, the water stream being injected with a jetvelocity of at least about 30 to 36.5 f.p.s. and at least about 500 to600 g.p.m. for a molten slag input rate of 2 to about 4 tons per minute,the water stream being injected with a jet velocity of at least about36.5 to 55 fps. and at least about 1200 to 1800 g.p.m. for a slag inputrate of 4 to about 7 tons per minute, and the water stream beinginjected with a jet velocity of at least about 55 to 61 f.p.s. and atleast about 1800 to 2000 g.p.m. for a slag input rate of 7-8 tons perminute; maintaining water accumulating in said receptacle at a levelbelow said jet stream while said molten steel slag is being poured intothe receptacle so that the molten steel slag intercepts said jet streamabove water accumulated in the receptacle; and removing resultantgranulated slag particles from said receptacle n while the granulationkof the molten steel slag is in progress.

2. A method of handling molten steel slag as defined in claim l whereinwater for the granulation of the molten steel slag is provided at therate of 400 to 1600 g.p.m. per ton of slag per minute.

3. A method of handling molten steel slag as defined in claim l whereinwater for the granulation of molten steel slag is provided at the rateof about 900 to 1350` g.p.m. per ton -of slag per minute.

4. A method of handling molten steel slag as defined in claim l whereinwater for the granulation of molten steel slag is provided at the rateof at least about 1350 to 1600 g.p.m. per ton of steel slag input perminute.

5. A method of handling molten steel slag as defined in claim 1 whereinwater for the granulation of molten steel slag is provided at the rateof about 400 to 1600 g.p.m. per ton of steel slag input per minute withall the water being introduced to the receptacle by means of lat leastone fiat water jet stream intercepting the molten steel slag.

6. A method of handling molten steel slag as defined in claim 1 wherein:for a steel slag input rate of 4 to about 7 tons per minute, water issupplied by means of two at jet streams, one over the other, each havinga jet velocity of at least about 36.5 to 55 f.p.s. with at least about11200 to 1800 g.p.m. water being injected by means of Iboth jet streams;and, for a molten slag input rate over 7 tons per minute, water issupplied by means of two flat jet streams, one over the other, eachhaving a jet velocity of at least about 55 to 6l f.p.s. with at leastabout 1800 to 2000 g.p.m. being supplied by means of both jet streams.

7. A method of handling molten steel slag as defined Y 25 stream and 40%Ito4 25% of said total water g.p.m. input being injected by means of thelower jet stream; each jet stream having at least a jet velocity inf.p.s. according to varying steel slag input rates as stated in claim 6.

9. A method of handling molten steel slag characterized in that itcomprises: pouring molten steel slag into a receptacle; injecting intosaid receptacle a plurality of flat water jet streams through aplurality of nozzles having substantially rectangular apertures anddispo-sed one over the other and spaced from each other with thetrajectory of said water jet streams intercepting the path of the slag;said Water jet streams being injected with a jet velocity of at leastabout 36.5 to 61 feet per second with about 1200 to 2000 g.p.m. of waterbeing introduced into the receptacle through said jet stream nozzles fora slag input rate of up to about 2 tons per minute, said two water jetstreams being injected into the receptacle with a jet velocity of atleast about 61 to 122 feet per second with about 2000 to 4000 g.p.m.being introduced through said jet stream nozzles for a slag input rateof 2 to about 4 tons per minute, and said water jet streams beinginjected into the receptacle with a jet velocity of at least about 91 to146 feet per second with about 3000 to 5000 g.p.m. being introducedthrough said jet stream nozzles for a molten steel slag input rate of 4to about 7 tons per minute; maintaining water accumulating in saidreceptacle at a level below the lowermost of said water jet streamnozzles while molten steel slag is being poured into the receptacle; andremoving resultant granulated steel slag particles from said receptaclewhile the granulation of the molten steel slag is in progress, at anaverage rate substantially equal to the average rate of molten slag inut.

p10. A method of handling molten steel slag as defined in claim 9wherein: the total quantity of water in gpm. is supplied according tovarying steel slag input rates as stated `in claim 9 by means of twoflat jet streams, one over the other, with 60% to 75% of said totalwater g.p.m. input being injected by means of the upper jet stream and40% to 25 of said total water gpm. input being injected by means of thelower jet stream; each jet stream having at least a jet velocity inf.p.s. according to varying steel slag input rates as stated in claim 9.

11. A method of handling molten steel slag from a steelmaking furnacecharacterized in that it comprises: pouring molten steel slag into areceptacle; injecting at least one flat jet stream of water into saidreceptacle so as to intercept said molten steel slag to granulate saidslag into particles; said water jet stream being injected at a rate ofat least 400 gpm. per ton of molten slag input per minute with a waterjet velocity ranging from at least about 25 f.p.s. for a slag input rateof up to 2 tons per minute to at least about 55-61 f.p.s. for a slaginput rate of up to about 8 tons per minute; maintaining the wateraccumulating in said receptacle at a level below said water jet streamat all times while molten steel slag is being poured into saidreceptacle so that the molten steel slag intercepts said jet streamabove the Water accumulated in said receptacle; and removing resultantgranulated slag particles from said receptacle while granulation of themolten steel slag is in progress, at a rate sufficiently ap proximatingthe rate at which molten slag is poured into the receptacle so as toprevent substantial build-up of granulated slag particles within saidreceptable.

12. An apparatus for handling rnolten steel slag from a steelmakingfurnace characterized iu that it comprises: slag granulator meansincluding a receptacle; means for pouring molten steel slag into saidreceptacle; means for injecting a plurality of fiat jet streams of Waterwith a trajectory intercepting the path of said molten slag and insufficient quantity to granulate said steel slag into particles, saidmeans including a plurality of jet nozzles each having a substantiallyrectangular aperture with a horizontal dimension which is large comparedto the vertical dimension thereof, with said jet nozzles disposed oneover 26 the other and spaced from each other; said means pouring themolten slag into the slag granulator receptacle without any substantialtrajectory transverse to the trajectory of said water jet streams; meansfor maintaining water accumulating in said granulator receptacle at alevel below the lowermost of said water jet nozzles while molten steelslag is being poured into the granulator receptacle; and means formoving the granulated slag particles through and agitating the waterbath accumulating in said receptacle and for removing granulated slagparticles from the receptacle, said means comprising a rake conveyordisposed within said granulator receptacle and including means movingthrough the receptacle below the level of the water bath accumulatingtherein and in a direction away from said jet nozzles so as to removegranulated slag particles from the region of interception of said moltenslag and lwater jet streams, said rake conveyor means operating toremove granulated slag at an average rate at least substantially equalto the rate molten steel slag is poured into said slag granulatorreceptacle.

13. In combination with an open hearth steelmaking furnace in a furnacebuilding having a charging oor in front of the furnace and a kitchenbelow such charging floor, the furnace having at least one door andspillway opening extending through said charging floor adjacent saidfurnace door for passage therethrough of molten front flush steel slagdischarged through said door .in operation, an apparatus for handlingsuch molten slag characterized in that it comprises: a slag granuilatorincluding a receptacle disposed in said kitchen and away from below saidslag spillway; slag transfer means movable lbetween a first position inwhich molten slag discharged through said spillway in the charging floorin operation will pour into said granulator receptacle and a secondposition in which such molten slag will not pour into said granulatorreceptacle; said granulator including 'means for directing at least onejet stream of water to intercept said molten slag poured into saidreceptacle and in sufficient quantity to granulate the slag intoparticles; means for limiting a water bath accumulating in saidreceptacle at all times during operation to a level below the region ofinterception of the molten slag by said water jet stream; and means forremoving `resultant granulated slag from said granulator receptacle andout of said kitchen while granulation of the slag is in progress atsubstantially the rate of molten slag input.

14. An apparatus for handling front flush and tap slag from an openhearth steelmaking furnace located in a furnace building as defined inclaim 13, the furnace back wall having a tap hole through which part ofthe slag is tapped into a steel ladle on said pit side after tapping ofthe Steel into said ladle, said slag handling apparatus furthercomprising: means for transferring tap slag from said ladle on said pitside of the furnace to said granulator means in said kitchen and theresubjecting the ladle tap slag to a jet stream of cooling medium insuicient quantity to granulate it into particles, with said granulatedslag removal means also removing the resultant granulated tap slag fromsaid granulator means and out of the kitchen and furnace building.

15. An apparatus for handling front flush and tap slag from an openhearth steelmaking furnace located in a furnace building, as defined inclaim 13, further cornprising: means on the pit side of the furnace forsubject- 1ng molten tap slag from said ladle to a jet stream of watersupplied in sumcient quantity to granulate the tap slag into particles;and means for transferring the re sultant granulated tap slag from thepit side of the furnace while granulation of the tap slag is inprogress, and removing it from the furnace building.

16. An apparatus combination as defined in claim 13, wherein said slagtransfer means comprises a movable chute having one portion thereofdisposable below said spillway opening in the charging door to receivefront flush slag discharged from the furnace and another chute portionextending to the granulator in the kitchen so as Z7' to pour moltenfront flush slag into said granulator receptacle, means being providedfor moving said one chute portion away from below said opening in thecharging oor so as to permit the molten slag to fall to below thefurnace.

References Cite by the Examiner UNITED STATES PATENTS 28 1,517,68912/1924 Welch 75-24 2,702,407 2/1955 Osborne 65-20 FOREIGN PATENTS562,523 8/1958 Canada. 161,401 10/1953 Sweden.

DONALL H. SYLVESTER, Primary Examiner.

G. R. MYERS, Assistant Examiner.

1. A METHOD OF HANDLING MOLTEN STEEL SLAG CHARACTERIZED IN THAT ITCOMPRISES: POURING MOLTEN STEEL SLAG INTO A RECEPTACLE; INJECTING ATLEAST ONE JET STREAM OF WATER INTO SAID RECEPTABCLE SO AS TO INTERCEPTSAID MOLTEN STEEL SLAG TO GRANULATE THE MOLTEN SLAG INTO PARTICLES; THEWATER STREAM BEING INJECTED WITH A JET VELOCITY OF AT LEAST ABOUT 25.0F.P.S. AND AT LEAST ABOUT 400 G.P.M. FOR A MOLTEN SLAG INPUT RATE OF UPTO ABOUT 2 TONS PER MINUTE, THE WATER STREAM BEING INJECTED WITH A JETVELOCITY OF AT LEAST ABOUT 30 TO 36.5 F.P.S. AND AT LEAST ABOUT 500 TO600 G.P.M. FOR A MOLTEN SLAG INPUT RATE OF 2 TO ABOUT 4 TONS PER MINUTE,THE WATER STREAM BEING INJECTED WTH A JET VELOCITY OF AT LEAST ABOUT36.5 TO 55 F.P.S. AND AT LEAST ABOUT 1200 TO 1800 G.P.M. FOR A SLAGINPUT RATE OF 4 TO ABOUT 7 TONS PER MINUTE, AND THE WATER STREAM BEINGINJECTED WITH A JET VELOCITY OF AT LEAST ABOUT 55 TO 61 F.P.S. AND ATLEAST ABOUT 1800 TO 2000 G.P.M. FOR A SLAG INPUT RATE OF 7-8 TONS PERMINUTE; MAINTAINING WATER ACCUMULATING IN SAID RECEPTACLE AT A LEVELBELOW SAID JET STREAM WHILE SAID MOLTEN STEEL SLAG IS BEING POURED INTOTHE RECEPTACLE SO THAT TE MOLTEN STEEL SLAG INTERCETS SAI DJET STREAMABOVE WATER ACCUMULATED IN THE RECIPTACLE; AND REMOVING RESULTANTGRANULATED SLAG PARTICLES FROM SAID RECEPTACLE WHILE THE GRNULATION OFTHE MOLTEN STEEL SLAG IS IN PROGRESS.
 13. IN COMBINATION WITH AN OPENHEARTH STEELMAKING FURNACE IN A FURNACE BUILDING HAVING A CHARGING FLOORIN FRONT OF THE FURNACE AND A KITCHEN BELOW SUCH CHARGIDNG FLOOR, THEFURNACE HAVING AT LEAST ONE DOOR AND SPILLWAY OPENING EXTENDING THROUGHSAID CHARGING FLOOR ADJACENT SAID FURNACE DOOR FOR PASSAGE THERETHROUGHOF MOLTEN FRONT FLUSH STEEL SLAG DISCHARGED THROUGH SAID DOOR INOPERATION, AN APPARATUS FOR HANDLIN SUCH MOLTEN SLAG CHARACTERIZED INTHAT IT COMPRISES; A SLAG GRANULATOR INCLUDING A RECEPTACLE DISPOSED INSAID KITCHEN AND AWAY FROM BELOW SAID SLAG SPILLWAY; SLAG TRANSFER MEANSMOVABLE BETWEEN A FIRST POSTION IN WHICH MOLTEN SLAG DISCHARGED THROUGHSAID SPILLWAY IN THE CHARGING FLOOR IN OPERATION WILL POUR INTO SAIDGRANULATOR RECEPTACLE AND A SECOND POSITION IN WHICH SUCH MOLTEN SLAGWILL NOT POUR INTO SAID GRANULATOR RECEPTACLE; SAID GRANULATOR INCLUDINGMEANS FOR DIRECTING AT LEAST ONE JET STREAM OF WATER TO INTERCEPT SAIDMOLTEN SLAG POURED INTO SAID RECEPTACLE AND IN SUFFICIENT QUANTITY TOGRANULATE THE SLAG INTO PARTICLES; MEANS FOR LIMITING A WATER BATHACCUMULATING IN SAID RECEPTACLE AT ALL TIME DURING OPERATION TO A LEVELBELOW THE REGION OF INTERCEPTION OF THE MOLTEN SLAG BY SAID WATER JETSTREAM; AND MEANS FOR REMOVING RESULTANT GRANULATED SLAG FROM SAIDGRANULATOR RECEPTACLE AND OUT OF SAID KITCHEN WHILE GRANULATION OF THESLG IS IN PROGRESS AT SUBSTANTIALLY THE RATE OF MOLTEN SLAG INPUT.